Um- you might want to add that you have to unlock the plugin as well as the PMXE or PMDE program by going to the zip file, right clicking and going to properties, then going down and unlocking the file and clicking apply and 'OK'. ;v; If you don't do that, the plugin won't work.

I've tried this to a MIRIAM model, but after testing it out on MMD, it didn't do anything, she was still functioning the way she was before

And I've tried this to anon, kanon and MEIKO V3, but it messed with the weighting I think. It was really weird, some parts of their clothes are flying in ways they shouldn't >.< Any idea how to fix these issues?

Could be that a few of the bones you were going to add were here before, but broken, and you didn't see them. For example, if the original (X) rotation bones in arms are broken and you'll try to add them again using the plugin, without cleaning them before, the plugin probably won't do much, it won't 'overwrite' the bones' properties and such.

I have PMD editor version 1.39, version 0.94b, and the English version found here on DA.

None of them will run the plugin. I get an error upon launch saying it can't load any of the dll files correctly, yet I put them where you said. Do I have the wrong PMD version? This is really frustrating...

Maybe you could upload the zip to mediafire and take it down once I've got it? Or are you okay with emailing it? I just really need this to work so I can release the models I've been working on. They both need second upper body bones and this would help tremendously.